Abstract
Six new 1-aroyl-4-(4-meth-oxy-phen-yl)piperazines have been prepared, using coupling reactions between benzoic acids and N-(4-meth-oxy-phen-yl)piperazine. There are no significant hydrogen bonds in the structure of 1-benzoyl-4-(4-meth-oxy-phen-yl)piperazine, C18H20N2O2, (I). The mol-ecules of 1-(2-fluoro-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19FN2O2, (II), are linked by two C-H⋯O hydrogen bonds to form chains of rings, which are linked into sheets by an aromatic π-π stacking inter-action. 1-(2-Chloro-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19ClN2O2, (III), 1-(2-bromo-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H19BrN2O2, (IV), and 1-(2-iodo-benzo-yl)-4-(4-meth-oxyphen-yl)piperazine, C18H19IN2O2, (V), are isomorphous, but in (III) the aroyl ring is disordered over two sets of atomic sites having occupancies of 0.942 (2) and 0.058 (2). In each of (III)-(V), a combination of two C-H⋯π(arene) hydrogen bonds links the mol-ecules into sheets. A single O-H⋯O hydrogen bond links the mol-ecules of 1-(2-hy-droxy-benzo-yl)-4-(4-meth-oxy-phen-yl)piperazine, C18H20N2O3, (VI), into simple chains. Comparisons are made with the structures of some related compounds.
Highlights
Piperazines are found in a wide range of compounds which are active across a number of different therapeutic areas such as antibacterial, antidepressant, antifungal, antimalarial, antipsychotic, and antitumour activity (Brockunier et al, 2004; Bogatcheva et al, 2006), and a number of these areas have recently been reviewed (Elliott, 2011; Kharb et al, 2012; Asif, 2015; Brito et al, 2019). 1-(4-Methoxyphenyl)piperazine has been found to inhibit the re-uptake and accelerate the release of monoamine neurotransmitters such as dopamine and serotonin, with a mechanism of action similar to that of recreational drugs such as amphetamines, but with significantly lower abuse potential (Nagai et al, 2007)
In the 2-chloro derivative (III), the benzoyl substituent is disordered over two sets of atomic sites having refined occupancies for the crystal selected for data collection of 0.942 (2) and 0.058 (2): in these two disorder forms, the chloro substituents occupy sites on opposite sides of the adjacent aryl ring (Fig. 3)
Each can be refined using the atomic coordinates of another as the starting point. These three structures exhibit several minor differences: firstly, the benzoyl group is disordered over two sets of atomic sites in (III), but not in (V); in (IV), the disorder was found to be very minor, ca 1.6%, such that attempted refinement of this small fraction was regarded as unrealistic and the ordered model was preferable
Summary
Piperazines are found in a wide range of compounds which are active across a number of different therapeutic areas such as antibacterial, antidepressant, antifungal, antimalarial, antipsychotic, and antitumour activity (Brockunier et al, 2004; Bogatcheva et al, 2006), and a number of these areas have recently been reviewed (Elliott, 2011; Kharb et al, 2012; Asif, 2015; Brito et al, 2019). 1-(4-Methoxyphenyl)piperazine has been found to inhibit the re-uptake and accelerate the release of monoamine neurotransmitters such as dopamine and serotonin, with a mechanism of action similar to that of recreational drugs such as amphetamines, but with significantly lower abuse potential (Nagai et al, 2007). 1-(4-Methoxyphenyl)piperazine has been found to inhibit the re-uptake and accelerate the release of monoamine neurotransmitters such as dopamine and serotonin, with a mechanism of action similar to that of recreational drugs such as amphetamines, but with significantly lower abuse potential (Nagai et al, 2007). With these considerations in mind, we have synthesized and characterized a series of closely related 1-aroyl-4-(4-methoxyphenyl)piperazines, using a straightforward coupling reaction between N-(4-methoxyphenyl)piperazine and a benzoic acid, promoted by 1-(3-dimethylaminopropyl)-3-ethylcarbodimide as the dehydrating agent.
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